The most popular COVID-19 antiviral is Paxlovid (nirmatrelvir [PF-07321332] and ritonavir). The manufacturer of the drug, Pfizer Inc. (NYSE: PFE), anticipates selling about $22 billion worth of Paxlovid this year. Complicating matters, however, is the failure of the drug to meet its primary endpoint of self-reported, sustained alleviation of all COVID-19 symptoms for four consecutive days in the…